1. Field of the Invention
The present invention relates to a general purpose low, medium and high voltage vacuum transfer switch. More particularly, the present invention relates to a mechanically interlocked transfer switch. Additionally, the present invention relates to a high speed transfer switch capable of switching circuits within sixteen (16) milliseconds (0.016 seconds). Additionally, the present invention relates to a transfer switch capable of switching circuits with voltages within the range of 600 Volts to 72,000 Volts.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Various industrial, institutional, commercial, medical, data processing, communications, defense, research and other electrical power sensitive facilities and installations typically require a source of standby or emergency power. The source of standby or emergency power typically must be capable of very fast startup and load acceptance from a non-operating condition, with energy derived from various means including singular or combined systems such as:                AC or DC prime or standby electrical generator sets powered by various prime movers, including but not limited to Diesel engines, gas engines, dual fuel engines, combustion turbines, steam turbines, water turbines and other prime movers;        Systems for directly storing energy, including but not limited to batteries, conventional or ultra capacitors, flywheels, high pressure nitrogen or other gas accumulators or receivers, fluids stored at high differential heads, and suitable stored indirect sources of energy, including hydrocarbon fuels such as Diesel oil, compressed natural gas (CNG), Butane, Propane, Hydrogen and other fuels;        Systems such as Uninterruptible Power Systems (UPS) for converting, conditioning, switching and otherwise making available high quality electrical power with minimal interruption, deriving their source of stored energy from one or more of the sources described above; and        Standby or emergency power systems referred to hereinabove being capable of very fast, reliable and preferably mechanically interlocked switching from a source of normal, utility electrical supply over to a standby or emergency power supply, wherein re-transfer to the normal supply must also be accomplished with the same speed and with mechanical interlocking.        
Alternatively or additionally, such electrical power sensitive facilities and installations may utilize or employ multiple independent incoming utility service feeders to provide utility electrical service from two (2) or more different utility sources. Such incoming utility feeders may provide electrical power at voltages typically ranging from nominal 5 kV to nominal 72 kV.
Any or all of the electrical power sensitive facilities and installations referred herein as well as conventional, non-sensitive installations may derive first cost and continuing economic, operational and reliability benefits by use of high-speed, mechanically interlocked low, medium or high voltage transfer switches. In certain cases, operation or reliability of various downstream feeder and/or distribution circuits may derive benefits from application of such high speed transfer switching.
Similarly, with transfer switches, the circuit to a load or substation can be broken upon the application of a manual force to a button or lever of the switch or by an automatic relay which actuates the switch. The activation of the switch changes the energy source from a first source to a second source to the load or substation. Alternatively, the transfer switch can change the load from a first load to a second load. The switch can be used to maintain a power flow without completely shutting down the system. Even in the event of repairs or interruptions, the power collection can be maintained.
The interruption of electrical power circuits has always been an effect of either a circuit breaker or switch, whether as a protective measure or a power management decision. In earliest times, circuits could be broken only by separation of contacts in air followed by drawing the resulting electric arc out to such a length that it can no longer be maintained. The basic problem is to control and quench the high power arc. This necessarily occurs at the separating of contacts of a switch or breaker when opening high current circuits. Since arcs generate a great deal of heat energy which is often destructive to the contacts, it is necessary to limit the duration of the arc and to develop contacts that can withstand the effect of the arc time after time.
A vacuum switch or circuit breaker uses the rapid dielectric recovery and high dielectric strength of the vacuum. The pair of contacts are hermetically sealed in the vacuum envelope. An actuating motion is transmitted through bellows to the movable contact. When the electrodes are parted, an arc is produced and supported by metallic vapor boiled from the electrodes. Vapor particles expand into the vacuum and condense on solid surfaces. At a natural current zero, the vapor particles disappear and the arc is extinguished.
In the past, various patents have issued relating to such vacuum switches and circuit breakers. For example, U.S. Pat. No. 5,612,523, issued on Mar. 18, 1997 to Hakamata et al., teaches a vacuum circuit-breaker and electrode assembly. A portion of a highly conductive metal member is infiltrated in voids of a porous high melting point metal member. Both of the metal members are integrally joined to each other. An arc electrode portion is formed of a high melting point area in which the highly conductive metal is infiltrated in voids of the high melting point metal member. A coil electrode portion is formed by hollowing out the interior of a highly conductive metal area composed only of the highly conductive metal and by forming slits thereon. A rod is brazed on the rear surface of the coil electrode portion.
U.S. Pat. No. 6,048,216, issued on Apr. 11, 2000 to Komuro, describes a vacuum circuit breaker having a fixed electrode and a movable electrode. An arc electrode support member serves to support the arc electrode. A coil electrode is contiguous to the arc electrode support member. This vacuum circuit breaker is a highly reliable electrode of high strength which will undergoes little change with the lapse of time.
U.S. Pat. No. 6,759,617, issued on Jul. 6, 2004 to S. J. Yoon, describes a vacuum circuit breaker having a plurality of switching mechanisms with movable contacts and stationary contacts for connecting/breaking an electrical circuit between an electric source and an electric load. The actuator unit includes at least one rotary shaft for providing the movable contacts with dynamic power so as to move to positions contacting the stationary contacts or positions separating from the stationary contacts. A supporting frame fixes and supports the switching mechanism units and the actuator unit. A transfer link unit is used to transfer the rotating movement of the rotary shaft to a plurality of vertical movements.
U.S. Pat. No. 7,223,923, issued on May 28, 2007 to Kobayashi et al., provides a vacuum switchgear. This vacuum switchgear includes an electro-conductive outer vacuum container and a plurality of inner containers disposed in the outer vacuum container. The inner containers and the outer container are electrically isolated from each other. One of the inner vacuum containers accommodates a ground switch for keeping the circuit open while the switchgear is opened. A movable electrode is connected to an operating mechanism and a fixed electrode connected to a fixed electrode rod. Another inner vacuum container accommodates a function switch capable of having at least one of the functions of a circuit breaker, a disconnector and a load switch.
It is an object of the present invention to provide a vacuum transfer switch with integral high speed of a relatively low cost.
It is a further object of the present invention to provide a vacuum transfer switch with an integral high speed that is mechanically interlocked.
It is a further object of the present invention to provide a vacuum transfer switch with an integral high speed which minimizes energy losses.
It is still a further object of the present invention to provide a vacuum transfer switch that can be applied and operated in the range of 0.6 kilovolts to 72 kilovolts.
It is still another object of the present invention to provide a vacuum transfer switch that is effective for use in association with installations such as described earlier.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.